I cannot help as I early on (back when all I had was the X100) I learned that I didn't want to use auto ISO. With the fw change to give us the Fn button to control ISO it is too easy to change to rely on the camera. Auto ISO is not a strong suit with X cameras.

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X100 XPro1; 60mm Macro, 35mm f1.4XE1; Kit Zoom

Well, I only shoot Auto ISO with my X100, and use my Fn button to toggle the ND filter and my other raw button to select the "film" type. The X100 has a proper Auto ISO feature IMO as it allows for the selection of a minimum shutter speed. I do not want to fiddle and take time to adjust the ISO on every shot if the camera can do the job well. I am waiting for Fuji to improve the XE1 Auto ISO with a firmware upgrade before I buy this camera.